High-frequency adventitious shoot bud induction and shoot elongation of Chile pepper (Capsicúm annuum L.)

In vitro plantlet regeneration was obtained from cultured cotyledon and young leaf explants of five Indian chile pepper cultivars (Capsicum annuum L. evs. Gujarat-1, Gujarat-2, Guntur-4, Selection-49, and Jwala). Adventitious shoot buds (ASB) were regenerated directly from cotyledon and young leaf explants in all the five cultivars on media containing benzyladenine (BA) alone or in combination with 1-naphthaleneacetic acid (NAA). Regeneration frequency was highly influenced by cultivar explant type, media combination and their interactions, except the interaction between cultivar and explant, for number of ASB per explant. Percent contribution of individual source suggested that selection of explant type followed by medium combination and cultivars was essential for obtaining high-frequency ASB induction. Across different cultivars the young leaf explant was found to be the most responsive explant, while Murashige and Skoog (MS) medium containing BA alone (17.8, 26.6, and 35.5 μM) was found to be the best medium for the production of maximum number of ASB. Between the two explants, shoot elongation was observed with ASB obtained from young leaf explants on MS medium containing BA (2.2 and 4.4 μM) and gibberellie acid (GA3) (1.4, 2.9, 4.3 and 5.8 μM). The MS medium fortified with 4.4 μM BA+2.9μM GA3 was optimum for shoot elongation. Elongated shoots were rooted on liquid MS medium supplemented with 2.9 μM indole-3-acetic acid (IAA) and successfully established ex vitro

Factors affecting adventitious shoot and root formation from the avocado cultivar 'Hass' (Persea americana. Mill.) in vitro

Avocado is an important crop that would benefit from the production of new, superior cultivars; however, conventional breeding techniques for this species are slow. The development of cultivars would be aided if an efficient tissue culture system could be developed. This study describes the use of embryonic material and variations in tissue culture conditions on in vitro shoot development. The production of shoot bases from embryonic shoot tissues permitted the production of multiple adventitious shoots from one explant, with up to ten shoots developing from one base. Shoot development was significantly affected by the hormone regime on which the embryonic shoot bases were cultured. Modified MS medium supplemented with 1.0 mg benzyladenine/litre, 0.1 mg IBA/litre, 0.1 mg GA3/litre was optimum for adventitious shoot development. Cutting the embryonic shoot tissue transversely significantly increased multiple shoot growth compared to longitudinal dissection. The addition of 0.1% PVP reduced tissue browning and necrosis. Root formation was achieved from 75% of adventitious microcuttings with the use of IBA and putrescine, either as a pretreatment or in the culture medium. The combination of these methods should provide an efficient way of achieving multiple, adventitious shoot and root formation in vitro